Help with tire size

[Jaysonb]

I picked up a 80 short stepper, it has 2" drop spindles with 2" drop springs in the front, and the rear axle is flipped, with about 2" lowering blocks as well. It has rally wheels on it now, but I would like to put some 18x8 mb old school wheels on it. I think it looks good when people put bigger tires in the rear, but I would like to find a good size 18" tire I can put on all 4 corners. The wheels are 18x8, with 0 offset. They also have a 20x9.5 with a 0 offset that would look good in the rear, but I'm not sure what size tires would look good. Thanks for any help.